Effects of heat-affected zone peak temperatures on the microstructure and properties of 2090 Al alloy

Abstract

The influence of the heat-affected zone (HAZ) thermal cycles on the microstructure and mechanical properties of 2090 Al alloy has been investigated. Emphasis is placed on the effects of the HAZ peak temperatures on the T3 and T8 tempered 2090. The HAZ thermal cycles were simulated using a Gleeble, and tensile tests were conducted at 293 and 77 K. The difference in properties between the HAZ and the base metal is primarily caused by the dissolution of strengthening phases. At 578 K, degradation in strength occurs due to dissolution of δ’ phase and, at 773 K, due to dissolution of T1 phase. The thermal cycle to 648 K leads to an observable growth of T1 phase, but the volume fraction is too low to be an effective strengthener. As a result, at the 293 K test temperature, the base metal (BM) tempers become irrelevant with the peak temperatures above 578 K, and the ultimate tensile strength (UTS) curves of both the BM-T3 and BM-T8 coincide and follow the same trend up to 853 K. At the 77 K temperature, the strength and elongation of the BM and the thermally cycled specimens in the T3 and T8 tempered conditions follow the trend seen at 293 K and exhibit higher strengths and elongations.